Dartmouth Engineers Develop New Device for Climate Change Research

Obbard’s team will be first to transport sea ice at its original temperature

Early next year, Dartmouth engineering professor Rachel Obbard and her team will become the first to transport sea ice cores from the Arctic to the lab at their original temperature—an important achievement in the effort to better understand climate change.

Sea ice, which can be as much as five meters thick, controls the exchange of heat, fluid, gases and chemicals between the ocean and the atmosphere. The loss of thick multiyear sea ice has important implications for the Earth’s climate.

“Sea ice plays an enormous role in ocean circulation and global climate,” says Obbard. Analysis of the ice, however, has been limited by the difficulties associated with retrieving, transporting and curating it. “Until we can get the sea ice to the lab with its original pore structure intact, we can't accurately model that structure.”

To accurately model the complex brine networks in sea ice, the ice must be maintained at its original temperature following extraction, something that hasn’t been possible until now. In February, Obbard and a team from Thayer, including PhD student Ross Lieb-Lappen and one or two undergraduate students, will become the first to transport sea ice at its original temperature of minus 2 degrees Celsius at its base and minus 35 degrees Celsius at its top. The group plans to collect approximately 12 sea ice cores from off the coast of Barrow, Alaska and drive them across the country to Dartmouth’s Ice Research Laboratory at Thayer.

To do that, Obbard will use a system she and her students have spent the last three years inventing called the Ice Core Extraction while Maintaining In-Situ Temperature Transitions (ICE-MITT).

Powered by a generator inside the truck, a set of two-by-four-foot insulated boxes each house two one-meter-long sections of ice core. The ice cores are attached to Peltier thermoelectric devices with fans that draw heat out and remove it from the box. The Peltier device, which looks like a small square plate, converts an applied electric voltage to a temperature difference between its two sides.

The initial design for the ICE-MITT began three years ago with a group of ENGS 21: Introduction to Engineering students who tackled the challenge of finding a way to maintain the temperature of ice cores. The team created a single-core Peltier-based system that was cooled with circulating liquid in coils like the ones you see on the back of a refrigerator. In the spring of 2012, Natalie Afonina Th’14, who was part of that original group and is now pursuing an MS with professor Ian Baker, took the ICE-MITT to the next design stage as an independent research project in ENGS 87: Undergraduate Investigations. She made significant progress on the control system, which is based on the open-source Arduino platform.

Then, last fall, an ENGS 89/90: Engineering Design Methodology and Project Initiation group took the ICE-MITT further, creating thermodynamic models and refining the unit’s power electronics, but then hit a snag when the coolant system wasn’t up to the job. Cook Engineering Design Center Fellow Gunnar Pope Th’14 ’16, who is now pursuing an MS with professor Ryan Halter, came on board in March to finish the design and build a working prototype. He replaced the liquid cooling system with an air-cooled one, improved the power and control electronics, and reduced the overall weight of the box.

Challenges, however, remain. “We hope to raise $40,000 to supplement our National Science Foundation (NSF) funding so we can build enough boxes to collect 12 first-year sea ice cores,” says Obbard. “Contributions could take on the form of sponsorship of individual ICE-MITT boxes or travel funds for the truck or trailer, hotel or fuel. We are also looking for additional opportunities for outreach along our route.”

Obbard and her crew will make stops along their road trip to educate K-12 students and the public about sea ice and climate change.

“We plan to hold outreach events at schools, libraries and science museums in a number of cities, among them Fargo, North Dakota, Madison, Wisconsin, Chicago and Cleveland,” says Obbard. “We will give presentations explaining sea ice, its role in the Arctic region and the global environment, and the specifics of our particular project.” The team will share a slideshow of their six-week field campaign, and show attendees their ice-coring device and the ICE-MITT system. Children and adults will get to handle sea ice, examine polymer models of brine channels, and try on the group’s expedition clothing.

This work is part of a three-pronged project for the NSF’s Division of Polar Programs that involves developing the ICE-MITT system, collecting a variety of sea ice cores from locations around Barrow, and analyzing those cores using micro-computed tomography and applied mathematics. Dartmouth Professor of Mathematics Scott Pauls is collaborating with the group to characterize the topology of brine networks in sea ice.

“The results of our work will help scientists understand how pore networks are organized in sea ice,” says Obbard. “We are interested in porous materials in general and in the role brine networks play in sea ice, large and small. Brine channels form a habitat for marine microorganisms and contribute to the sea ice cover’s role in the local, regional and global environment.

“What we find will help other scientists better understand the sea ice melt rate, the ocean-ice-atmosphere system, the photosynthetic marine biota and the higher food web that depends on it, and even the distribution and fate of pollutants,” she adds.